1. Field of the Invention
The present invention relates to a cleaning device for a semiconductor inspection device and a washing liquid used therefor. More specifically, the present invention relates to a cleaning device for a probe needle of a probe card and a washing liquid used therefor.
2. Description of the Background Art
Conventionally, a device called a probe card has been used in the inspection process of semiconductor devices. FIG. 16 is a cross sectional view of a conventional probe card. Referring to FIG. 16, the conventional probe card has an opening 114 formed almost at the center of a substrate 116. In the periphery of opening 114, a plurality of probe needles 111 are provided toward the center of opening 114. Probe needle 111 is connected to a terminal (not shown) arranged in the periphery of substrate 116 through a wiring. In inspecting a semiconductor device, the terminal is connected to an inspection device called a prober. The probe card is arranged opposite to a surface of the semiconductor device to be inspected and is also arranged so that the tip of probe needle 111 comes in contact with an electrode formed on the surface of the semiconductor device. The electrical characteristics of the semiconductor device are thus inspected through probe needle 111 in contact with the electrode formed on the surface of the semiconductor device.
FIG. 17 is a schematic view illustrating conventional probe needle 111 shown in FIG. 16. Referring to FIG. 17, the lead portion of the probe needle has a diameter D of approximately 0.25 mm, the end of the probe needle has a length L of approximately 7 mm, and the tip 112 of the probe needle that comes in contact with an electrode of a semiconductor device has a diameter d of approximately 30 xcexcm. The materials for the probe needle include tungsten or the like.
In inspecting a semiconductor device, tip 112 of the probe needle comes in contact with an electrode 131 formed on a surface of the semiconductor device, as shown in FIGS. 18 and 19. FIGS. 18 and 19 are schematic views illustrating how the tip of the probe needle comes in contact with the electrode formed on the surface of the semiconductor device. As shown in FIG. 18, electrode 131 formed on the surface of semiconductor device 132 is brought in contact with tip 112 of probe needle 111 by raising semiconductor device 132 toward probe needle 111. Electrode 131 of semiconductor device 132 is formed of aluminum, and a thin aluminum oxide layer 133 is formed on a surface of electrode 131. Since aluminum oxide layer 133 is an insulating layer, an aluminum layer 134 under aluminum oxide layer 133 cannot be brought into contact with tip 112 of probe needle 111 simply by pressing tip 112 of probe needle 111 against electrode 131 as shown in FIG. 18. Therefore, current cannot be passed from probe needle 111 to electrode 131.
Accordingly, semiconductor device 132 is typically further raised after tip 112 of probe needle 111 is brought into contact with electrode 131, as shown in FIG. 19. Probe needle 111 is thus elastically deformed and tip 112 of probe needle 111 is horizontally moved on electrode 131. Aluminum oxide layer 133 on the surface of electrode 131 is thus partially removed from the surface of electrode 131 to allow aluminum layer 134 which is the electrode body to come into direct contact with tip 112 of probe needle 111. The process shown in FIG. 19 will be referred to as an overdrive process hereinafter. In this manner, tip 112 of probe needle 111 has come into contact with electrode 131 in the conventional inspection process.
However, the overdrive process as shown in FIG. 19 causes part of aluminum oxide layer 133 removed from the surface of electrode 131 to adhere to tip 112 of probe needle 111 as shown in FIG. 20. When a foreign matter 113, such as aluminum oxide, which is an insulator thus adheres to tip 112 of probe needle 111, foreign matter 113 prevents the electrical connection between tip 112 of probe needle 111 and electrode 131 (see FIG. 19) of the semiconductor device, making it difficult to pass a prescribed current to electrode 131. Accordingly, repeated use of such a probe needle has disadvantageously resulted in an inaccurate inspection of semiconductor devices.
Accordingly, a probe needle cleaning operation has been performed so as to remove foreign matter 113 such as aluminum oxide from tip 112 of probe needle 111.
FIG. 21 is a cross sectional view of an abrasive sheet for probe needles that is used in a conventional probe needle cleaning operation. Referring to FIG. 21, the conventional abrasive sheet 135 for probe needles employs silicon rubber 136 as a matrix, and abrasive grains 137 such as artificial powdery diamond are dispersively arranged in silicon rubber 136. When tip 112 (see FIG. 20) of probe needle 111 (see FIG. 20) is stuck into abrasive sheet 135 prescribed times, foreign matter 113 (see FIG. 20) is scraped off the surface of probe needle 111 by abrasive grains 137 in abrasive sheet 135. Foreign matter 113 has conventionally be removed from tip 112 of probe needle 111 in this manner.
FIG. 22 is a flow chart of a conventional probe needle cleaning operation. Referring to FIG. 22, the conventional probe needle cleaning operation consists of four steps. At step 1, a probe card is arranged opposite to an abrasive sheet. At step 2, the tip of a probe needle is stuck into the abrasive sheet prescribed times. FIG. 23 is a schematic view showing the process of sticking the tip of the probe needle into the abrasive sheet prescribed times at step 2. As shown in FIG. 23, tip 112 of probe needle 111 is stuck into abrasive sheet 135 to allow foreign matter 113 such as aluminum oxide adhered to tip 112 of probe needle 111 to be scraped off by abrasive grains 137 in abrasive sheet 135.
At this stage after step 2, however, a viscous silicon rubber film 138 which is softened silicon rubber 136 (see FIG. 23) as the matrix of abrasive sheet 135 adheres to tip 112 of probe needle 111. A foreign matter 139 also adheres to silicon rubber film 138. Foreign matter 139 includes foreign matter 113 (see FIG. 23) such as aluminum oxide removed from tip 112 of probe needle 111 at step 2, abrasive grains 137 (see FIG. 23) removed from abrasive sheet 135, a removed portion of silicon rubber 136 (see FIG. 23) which is the matrix of abrasive sheet 135, and so on.
Accordingly, the conventional probe needle cleaning operation requires, as step 3, the step of spraying an organic solvent on the tip of the probe needle to remove foreign matter 139 (see FIG. 24) adhering to tip 112. FIG. 25 schematically shows how step 3 is performed.
As shown in FIG. 25, an organic solvent 140 is sprayed on tip 112 of probe needle 111 to dissolve silicon rubber film 138 and to remove silicon rubber film 138 and foreign matter 139 from tip 112 of probe needle 111.
When step 3 is completed, organic solvent 140 remains on probe needle 111 as shown in FIG. 26. Accordingly, the conventional probe needle cleaning operation carries out, as step 4, the step of blowing air to probe needle 111 (see FIG. 26) to dry organic solvent 140 (see FIG. 26) remaining on tip 112 of probe needle 111 and simultaneously blow off foreign matters and the like remaining on the surface of probe needle 111, as shown in FIG. 22.
The conventional probe needle cleaning operation has been performed in this manner.
Conventionally, foreign matter 113 has been removed from tip 112 of probe needle 111 by sticking tip 112 of probe needle 111 into abrasive sheet 135 as shown in FIG. 23. However, when the step of sticking is repeated several hundred times, the side surface and the bottom surface of tip 112 of probe needle 111 have been scraped by abrasive grains 137 in abrasive sheet 135 and tip 112 has been deformed. In the step of sticking, part of probe needle 111 may have been bent, causing variation in the height of tip 112 of probe needle 111.
When tip 112 of probe needle 111 is brought into contact with electrode 131 of semiconductor device 132 as shown in FIGS. 18 and 19, tip 112 of probe needle 111 has been changed in shape and varied in height. In this case, the contact between probe needle 111 and electrode 131 has not been perfect enough, making it difficult to pass a prescribed current to electrode 131.
Such a distorted probe needle needs to be repaired and readjusted by a manufacturer and therefore requires additional maintenance cost. It has been one reason for the increase in the manufacturing cost of a semiconductor device.
One object of the present invention is to provide a cleaning device for a probe needle of a probe card rarely causing abrasion and deformation of the tip of a probe needle and capable of improving a probe needle life.
Another object of the present invention is to provide a washing liquid used for a cleaning device for a probe needle of a probe card rarely causing abrasion and deformation of the tip of a probe needle and capable of improving a probe needle life.
A washing liquid for a probe needle of a probe card according to a first aspect of the present invention includes an aqueous solution containing phosphoric acid.
Accordingly, when a probe needle is immersed in the washing liquid and vibration is applied to the washing liquid in the cleaning method for a probe needle of a probe card described below, a foreign matter such as aluminum oxide adhering to the probe needle can be removed from the probe needle with little abrasion and deformation of the tip of the probe needle. As a result, abrasion and deformation of the tip of a probe needle in a probe needle cleaning operation can be prevented. Thus, a probe needle life can be improved.
In the washing liquid for a probe needle of a probe card according to the first aspect, the ratio of phosphoric acid with respect to water is preferably 36 milliliters/1 liter.
In the washing liquid for a probe needle of a probe card according to the first aspect, the aqueous solution may further contain chromic acid anhydride.
Accordingly, when the washing liquid is used in the cleaning method for a probe needle of a probe card described below, a foreign matter such as aluminum oxide adhering to a probe needle can be removed more efficiently from the probe needle with little abrasion and deformation of the tip of the probe needle. As a result, abrasion and deformation of the tip of a probe needle in a probe needle cleaning operation can be prevented. Thus, a probe needle life can be improved.
In the washing liquid for a probe needle of a probe card according to the first aspect, the ratio of phosphoric acid with respect to water may be 36 milliliters/1 liter, and the ratio of chromic acid anhydride with respect to water may be 20 grams/1 liter.
A cleaning device for a probe needle of a probe card according to a second aspect of the present invention includes a washing bath for storing a washing liquid for a probe needle including an aqueous solution containing phosphoric acid, and a vibration generating member for vibrating the washing liquid.
Accordingly, when the washing liquid is used, a foreign matter such as aluminum oxide adhering to a probe needle can be removed from the probe needle with little abrasion and deformation of the tip of the probe needle. When the washing liquid is vibrated, the washing liquid can be permeated more reliably into a border portion between a probe needle surface and a foreign matter. As a result, a foreign matter can be removed reliably from the tip of a probe needle, and abrasion and deformation of the tip of a probe needle in a probe needle cleaning operation can be prevented. Thus, a probe needle life can be improved. Further, when the washing liquid is vibrated, a foreign matter can be removed more reliably from the surface of the probe needle by the physical vibration.
In the cleaning device for a probe needle of a probe card according to the second aspect, the ratio of phosphorus acid with respect to water is preferably 36 milliliters/1 liter.
Since the washing liquid suitable for removing a foreign matter such as aluminum oxide from a probe needle is used, a foreign matter can be removed reliably from a probe needle.
A cleaning device for a probe needle of a probe card according to a third aspect of the present invention includes a washing bath for storing a washing liquid for a probe needle including an aqueous solution containing chromic acid anhydride and phosphoric acid.
Accordingly, when the washing liquid is used, a foreign mater such as aluminum oxide adhering to a probe needle can be removed from the probe needle with little abrasion and deformation of the tip of the probe needle. As a result, abrasion and deformation of the tip of a probe needle in a probe needle cleaning operation can be prevented. Thus, a probe needle life can be improved.
The cleaning device for a probe needle of a probe card according to the second or third aspect may further include a post-processing bath for storing a processing liquid for removing the washing liquid from a probe needle.
The cleaning device for a probe needle of a probe card according to the second or third aspect may further include a drying member for drying a probe needle.
In the cleaning device for a probe needle of a probe card according to the third aspect, the ratio of chromic acid anhydride with respect to water is preferably 20 grams/1 liter, and the ratio of phosphoric acid with respect to water is preferably 36 milliliters/1 liter.
Since the washing liquid suitable for removing a foreign matter such as aluminum oxide from a probe needle is used, a foreign matter such as aluminum oxide can be removed more reliably from a probe needle.
The cleaning device for a probe needle of a probe card according to the second or third aspect may further include a vibration generating member for vibrating the washing liquid or the processing liquid.
Since the vibration generating member for vibrating the washing liquid or the processing liquid is thus provided, the washing liquid can be vibrated when part of a probe needle is immersed in the washing liquid. Accordingly, the washing liquid can permeate more reliably into a border portion between a probe needle surface and a foreign matter, further facilitating removal of a foreign matter from the probe needle. At the same time, the physical vibration allows a foreign matter to be removed more reliably from the surface of the probe needle. When the processing liquid is vibrated when part of a probe needle is immersed in the processing liquid, the washing liquid can be removed more reliably from the probe needle.
The cleaning device for a probe needle of a probe card according to the second or third aspect may further include a temperature controlling member for controlling the temperature of the washing liquid.
Accordingly, the temperature of the washing liquid can be controlled so as to keep a temperature suitable for removing a foreign matter from a probe needle. As a result, a foreign matter can be removed from the probe needle more reliably.
The cleaning device for a probe needle of a probe card according to the second or third aspect may further include a distance measuring member for measuring the distance between a probe needle and a washing liquid surface in the washing bath, a position adjusting member for controlling a position of at least either of the probe needle and the washing liquid surface, and a controlling member for controlling the position adjusting member based on information on the measured distance.
Accordingly, the distance between the probe needle and the washing liquid surface can be controlled precisely. As a result, the tip of the probe needle from which a foreign matter needs to be removed can be immersed reliably in the washing liquid. Thus, a foreign matter can be removed more reliably from the probe needle.
In the cleaning device for a probe needle of a probe card according to the second or third aspect, at least one of the washing bath and the post-processing bath may include a member for holding the surface of a portion of the washing liquid or the processing liquid in which a probe needle is immersed higher than the surface other than the portion.
Accordingly, the distance between a portion of the probe card other than the probe needle and the liquid surface can be made larger than the distance between the probe needle and the liquid surface. As a result, the washing liquid or the processing liquid can be prevented from adhering to the portion of the probe card other than the probe needle. It can prevent a probe card failure caused when the washing liquid or the processing liquid adheres to the portion of the probe card other than the probe needle.
A cleaning method for a probe needle of a probe card according to a fourth aspect of the present invention includes the steps of immersing at least part of a probe needle in a washing liquid for a probe needle of a probe card including an aqueous solution containing phosphoric acid, and holding at least part of the probe needle immersed in the washing liquid while vibrating the washing liquid.
Accordingly, a foreign matter such as aluminum oxide adhering to a probe needle can be removed from the probe needle with little abrasion and deformation of the tip of the probe needle. As a result, abrasion and deformation of the tip of a probe needle in a cleaning operation can be prevented. Thus, a probe needle life can be improved.
Since the washing liquid is vibrated, the washing liquid can permeate more reliably into a border portion between a probe needle surface and a foreign matter, further facilitating removal of a foreign matter from the probe needle. At the same time, the physical vibration allows a foreign matter to be removed more reliably from the surface of a probe needle.
In the cleaning method for a probe needle of a probe card according to the fourth aspect, the ratio of phosphoric acid with respect to water is preferably 36 milliliters/1 liter.
Since the washing liquid suitable for removing a foreign matter such as aluminum oxide from a probe needle is used, a foreign matter can be removed reliably from a probe needle.
A cleaning method for a probe needle of a probe card according to a fifth aspect of the present invention includes the steps of heating a washing liquid for a probe needle of a probe card including an aqueous solution containing chromic acid anhydride and phosphoric acid, immersing at least part of a probe needle in the heated washing liquid, and holding at least part of the probe needle immersed in the washing liquid.
Accordingly, a foreign matter such as aluminum oxide adhering to a probe needle can be removed from the probe needle with little abrasion and deformation of the tip of probe needle. As a result, abrasion and deformation of the tip of a probe needle in a cleaning operation can be prevented. Thus, a probe needle life can be improved.
In the cleaning method for a probe needle of a probe card according to the fifth aspect, the temperature for heating the washing liquid is at least 95xc2x0 C. and the time for holding at least part of the probe needle immersed in the washing liquid is at least 10 minutes.
Accordingly, a foreign matter such as aluminum oxide can be removed more reliably from a probe needle.
In the cleaning method for a probe needle of a probe card according to the fifth aspect, the ratio of chromic acid anhydride with respect to water is preferably 20 grams/1 liter, and the ratio of phosphoric acid with respect to water is preferably 36 milliliters/1 liter.
The cleaning method for a probe needle of a probe card according to the fourth or fifth aspect may further include the steps of measuring the distance between a probe needle and a washing liquid surface, and controlling a position of at least either of the probe needle and the washing liquid surface based on information on the measured distance.
Accordingly, the distance between the probe needle and the washing liquid surface can be controlled more precisely. As a result, the portion of the probe needle to be cleaned can be immersed reliably in the washing liquid. Thus, a foreign matter such as aluminum oxide can be removed more reliably from a probe needle.
The cleaning method for a probe needle of a probe card according to the fifth aspect may further include the step of vibrating the washing liquid when at least part of the probe needle is immersed in the washing liquid.
When the washing liquid is thus vibrated, the washing liquid can permeate further in a border portion between a probe needle surface and a foreign matter, further facilitating removal of a foreign matter. At the same time, the physical vibration of the washing liquid allows more reliable removal of a foreign matter from the surface of a probe needle.
The foregoing and other objects, features, aspects and advantages of the present invention will become more apparent from the following detailed description of the present invention when taken in conjunction with the accompanying drawings.